Magnetic field phenomenology: from the Universe to laboratory experiments

磁场是天体物理学和实验室等离子体的普遍特征，正如漫射无线电同步辐射和法拉第旋转观测所揭示的那样。这些场的能量密度通常与它们所嵌入的等离子体的流体运动的能量密度相当，使得磁场在发光物质的动力学中发挥重要作用。这些场是如何被创造和放大的仍然是一个谜。据信，湍流发电机行动可以有效地放大磁场，这是由我们在过去几年中进行的新的实验室实验支持。因此，今天在天体中观测到的磁场很可能是由微小的初始种子产生的。尽管如此，这些种子的起源仍然不清楚--人们提出了各种各样的等离子体过程。此外，这种放大过程不可能发生在宇宙空隙中，那里的等离子体密度太小，发电机无法工作。这些考虑是一个更基本问题的一部分，即在湍流级联中，大尺度注入可压缩等离子体的能量如何在小尺度运动之间分配，磁场和压缩波动，并通过宇宙射线消散。事实上，宇宙中存在高能粒子是一个公认的事实。导致这种高能粒子的确切机制仍然存在争议。虽然许多不同的过程可能会导致宇宙射线加速，但目前的理解是湍流和磁场在激发星际介质中的电子和离子方面起着至关重要的作用。我们计划使用多策略方法来解决这个问题，重点是：1.开发新的理论模型，在宇宙中产生磁场，应用等离子体物理过程（如返回电流，斜压效应和/或湍流发电机），并超越它们（例如，使用非标准模型物理）。我们将研究发生在早期宇宙中的过程以及发生在超新星遗迹中的过程。将这些模型嵌入到模拟代码中-特别是细胞中的颗粒（OSIRIS和/或EPOCH），并预测可测量的数量，这些数量可以根据观察和实验室实验进行测试。例子是磁场的光谱，或次级过程，如光子（x射线）的生产。3.了解磁场产生、放大和粒子加速之间的相互作用--例如二阶费米加速--并开发可以在高功率激光设备上进行实验验证的现象学模型。

Magnetic fields are an ubiquitous feature of astrophysical and laboratory plasmas, as revealed by diffuse radio-synchrotron emission and Faraday rotation observations. The energy density of these fields is typically comparable to the energy density of the fluid motions of the plasma in which they are embedded, making magnetic fields essential players in the dynamics of the luminous matter. How such fields are created and amplified remains a mystery. It is believed that turbulent dynamo action can efficiently amplify magnetic fields and this is supported by novel laboratory experiments that we have performed in the past few years. Thus the magnetic fields observed in astronomical bodies today could plausibly have arisen from tiny initial seeds. Still, the origin of such seeds remains unclear - and a variety of plasma processes have been proposed, Moreover, such amplification process cannot occur in cosmic voids, where the plasma density is too small for dynamo to become operative.These considerations are part of a more fundamental question of how the energy injected at large scales into a compressible plasma is partitioned, in a turbulent cascade, between small-scale motions, magnetic and compressive fluctuations, and dissipated via cosmic rays. Indeed, the presence of energetic particles in the Universe is a well established fact. The exact mechanism that leads to such high energy particles remains controversial. Although many different processes may result in cosmic ray acceleration, the current understanding is that turbulence and magnetic fields play an essential role in energizing both the electrons and ions present in the interstellar medium.We plan to tackle this problem using a multi-strategy approach that focuses on:1. Developing novel theoretical models for magnetic field generation in the Universe that applies plasma-physics processes (such as returns currents, baroclinic effects and/or turbulent dynamo) and go beyond them (for example, using non-standard model physics). We will investigate processes that occurs in the early Universe as well those that occurs in supernova remnants.2. Embed these models into simulation codes - particularly particle-in cell (OSIRIS and/or EPOCH) and predict measurable quantities that can be tested against observations and laboratory experiment. Examples are the spectrum of the magnetic field, or secondary processes such as photon (x-ray) production.3. Understand the interplay between magnetic field generation, amplification and particle acceleration - for example second order Fermi acceleration - and develop phenomenological models that can be validated with experiments on high-power laser facilities.This project fits "Plasmas and lasers"